Aquaponics, worms and E. coli

I have been made aware of a section in the latest newsletter of an aquaponics trainer making some rather interesting statements around the risk of introducing "deadly" E. coli HO157:H7 into aquaponics systems through the introduction of worms.

Like most promotional material, it contains enough reference to some form of correct base statement to make their argument appear compelling, but I have found the way that the section was written distressing in many ways. On one front, we are trying our level best to ensure food safety and hygene in our units and to educate people on the safety of aquaponic production methods. To have someone from within the community write something down the line of "if you dare put worms in your system you run a very real risk of introducing a deadly pathogen into aquaponics" is not conducive to building a fair and realistic impression of aquaponic production methods. Worms in media beds have been in use for many years outside of the design of the group in question, with no reports of any health issues.

The inference made was that (without stating how many worm growers use cattle poo) red wrigglers are likely or potentially all grown in manure from corn fed cattle and this all contains the "man made" (?????!) strain of E. coli that will then most likely survive the transfer from worm to your system where you will contaminate your crops, your family or your customers. If you are extra unlucky, a fly from a pasture containing corn fed cattle poo will also do the trick (then why bash the worms?) if they can make the trip in under 10 seconds.

The article would have had more use if it simply said something down the line of "pick your worm supplier carefully - if you are cautious about E. coli, steer clear of using worm growers that cannot guarantee that their worms were not fed corn-fed cow poo from feedlots." I do not know what the ratio is of worm producers that potentially use this feed method compared to those that do not, but if it is the case that very few follow this practice, this article borders on reckless. Then one can write follow-ups warning people on the next one in a gazilion risk such as a bird-flu contaminated duck landing in your fish tank. As stated before, in theory, the conditions described in the text can potentially occur. Just as, in theory, a monkey can sit down in front of a typewriter, hammer away at it and write something recognisable. Not impossible, but likely?

I wrote a blog a while ago about the responsibility of perceived role models in the industry related to statements made and perceptions created from a "credible" source. This type of statement was exactly what I was talking about. Not worth the negativety and not worth the potential bad press and poor PR for what many aquaponic producers see as a staple - media filled beds with worms in them (is there a reason for this?). As a scientist, I would like to see some concrete evidence related to instances of the scenario described having been observed at worm farms and in aquaponic systems. If no such data exists, is this statement fair and accurate? Why was it made? I do not want to appear to downright rubbish their concerns, but I will appreciate a percentage risk description to back up this claim.

Replies to This Discussion

Wow! Thanks Converse and Sylvia for providing incredibly logical and educated explanations. What really seems to be the main issue in this article is the implication that the worms themselves are the culprit for potentially causing the incidence of E. coli H0157 in an aquaponic system whereas it is the introduction of the worms depending upon their origination that is the problem, not the worms themselves. Research concludes that worms actually reduce the incidence of E.Coli and other dangerous pathogens, certainly not that they generate them! So perhaps what would have been much more of an accurate assessment of the likely introduction of such pathogens is some external source producing the contamination. However if that is the reason for concern, then one must conclude that a system then must be impervious to any other sources of external contamination in order to be absolutely safe. A fly, a cat, or a child could just as easily or even more realistically be the fateful carrier of a pathogen.

Gina you speak of the fly the cat and the child. What about the fact that he actually climbs into the tanks. That would really not be acceptable. What about the birds that fly over and leave deposits on our plants. E coli H7 O157 is not the only bug that is a problem. Birds carry Salmonella. Read the story of Typhoid Mary and how she spread typhoid fever (Salmonella) to many people and she would escape when they locked her up. Drinking your own water proves nothing. You have become immune to it. Carey Ma talks about the local chinese being able to eat the local food and it nearly kills him. We are vulnerable to organisms but less likely to have problems if we practice good hygeine and don't allow manure of any kind near our systems. Most of the farms that were found to be infective they are now really sure how it got inl. I believe we are all sensable and will protect as best as possible. Even without putting worms in we get Gammarus , midge fly larvae, snails, and some other creatures. It is an eco system. Just make sure your worms have had a TB clearence and a drug screen and all will be fine.

No doubt Raychel. I easily could have added birds to the list of conspirators! Totally agree that good hygiene practices are imperative and never introducing manure into an aquaponic system. The simple fact remains that pathogens don't and won't get generated by the presence of red worms, there must be an introduction from something or someone and most often it is a human element that is at fault. Can you tell me where I can get those worms drug tested? I might need to make sure they are doing no funny stuff! ;-)

I got the article and came to the same conclusion of just bullshit. Someone please show me where ecoli comes in contact with ammonia and survives. Even if you did get a worm with ecoli in its system it would be flushed out and come in contact with the ammonia and be killed in short order. I have stated in other discussions that to date no ecoli has been transferred from aquaculture to a human in farming operations. It has always been the dirty handling that has been the cause. I hope the aquaponics association becomes able to provide some funding in the future to squash some of the nonesense like this article. Just my opinion.

David, I cannot speak for the entire Association's future plans and links to other institutions, but as a scientist (and current member of the board), I do believe that there will be many opportunities to link with credible institutions to set up experiments such as the one you suggest here. It is relatively easy to set up, but as with most things in life, WHO says it is almost more important as WHAT is determined through a study.

I will raise the suggestion in the next board meeting this week, but will have to be guided by the other members of the board (Somehow I think people will have an issue with results coming out of South Africa) in terms of possible agencies or institutions with whom we could collaborate in order to start working towards finding answers for these issues (or shall I say publish results to be used as benchmarks when something like this is published again).

David Waite said:

I got the article and came to the same conclusion of just bullshit. Someone please show me where ecoli comes in contact with ammonia and survives. Even if you did get a worm with ecoli in its system it would be flushed out and come in contact with the ammonia and be killed in short order. I have stated in other discussions that to date no ecoli has been transferred from aquaculture to a human in farming operations. It has always been the dirty handling that has been the cause. I hope the aquaponics association becomes able to provide some funding in the future to squash some of the nonesense like this article. Just my opinion.

@Kobus: I agree and thank you for reminding all of us to be more responsible and less negative. I for one know and admit I have written and posted stuff when we are not mentally fit, like 3-4AM or simply letting out frustration from the day or incident.

@ TLC: I understand your concern and generally agree with you especially that your systems are configured in a very small, simple loop compared to the great mother (nature).

Although I have used (fresh) rabbit and goat/ sheep pellets and even duck poo, with no apparent contamination, I believe in these practices/ principles. The first, keeping high dissolved oxygen and high water surface area ratio. The second is to identify and segregate functions. The third is to try to extract as much nutrient at the end of the cycle so that we can get a good clean start (water purification) and fourthly to keep the nutrient loop going but terminate the microbial cycle and get a fresh start with the community of “good” bugs at the beginning of the cycle.

I too am very keen to close the loop. Instead of being scared of things, I would rather make sure the compost is managed properly to make it safe. I have worms in my system and I even use worm castings as my start up bacteria source.

But I do understand that most worm bins don't really have a way to guarantee that the worms and worm castings harvested have not touched new uncomposted materials before getting harvested so some caution about the feed stock for the worms being transferred to an aquaponics system. Or caution about how a vermiponics system is set up so you are not attracting flys that might have come from a pile of doo doo before visiting the vermiponics. Basically make the worm feeding area fly proof or covered and non stinky in such a way as to avoid the pests in the first place.

See, I don't really think they are actually so negative about worms. I'm thinking they are more worried about people getting too carried away with vermiponics and creating an atmosphere where if there is an outbreak it may be too easy for fingers to get pointed at aquaponics even if aquaponics is not the actual culprit. Remember that a passing suspicion during one of these food born illness outbreaks can ruin farms even if the contaminated food had nothing to do with them and there isn't really any compensation when later the true source is found since the suspected food has usually already been destroyed.

TLC, Sylvia and Gina are my new fem idols. Always so positive and encouraging.

This is porb my last post on this site for another two weeks. I'm heading to Seattle for a week to take care of some things. Hope I have time to pop in.

Anyway, I'd like to point out that a well stocked, mature pool/ tank is a bowl of nutrient soup for many forms of life and it is up to us to keep it in balance and bring us rewards instead of sorrow.

Now I have a question. What do you all do with your (liquid and solid) mistakes (for a lack of better word)? Do you drain it to sewer or flush it out to field? Ditch and bury? Incinerate? Just curious.